I don't think anybody really knows how many firearms are in private hands in the US, nor how many people own these arms; kind of like after the collapse of the Soviet Union, no one has any clue how many AK-pattern rifles were made by the Eastern Bloc countries, the middle east (like the Iraqi Tabuk), China, the Norks, etc. Estimates are anywhere from 10 to 50 million rifles.

Of course, some were destroyed in any one of two dozen conflicts in Africa and Southeast Asia. The gun may be crude, but they were designed to be made and serviced in simple jungle and desert shops. Oh, and since around 1990, God knows how many were (legally) imported into the US and other Western countries. The 4473 form for long guns only mentions caliber, no make or model. Gun confiscation in the US is going to be next to impossible. Hell, they can't even keep convicted felons from getting guns, and they make up less than 1% of the population.